#include <iostream>

using namespace std;

void case_1(){
    int x = 10;
    cout<<"before enter block x val : "<<x<<endl;
    {
        cout<<"after enter block x val : "<<x<<endl;
        int x = 20;
        cout<<"after define new x in block x val : "<<x<<endl;
    }
}

int main(int argc, const char** argv) {
    case_1();
    return 0;
}